Axial compressor



July 9, E. C. COWLES ETAL AXIAL COMPRESSOR Filed Dec. 19, 1960 son SY RWM KE WOT N NN R ECL.: mm V G T WH@ A o/V\m Q5. H WHB T SP United States Patent O 3,097,359 AXIAL COMPRESSOR Ellsworth C. Cowles, Corning, and Ralph F. Voggenthaler, Painted Post, N.Y., assignors to Ingersoll-Rand Company, New York, N.Y., a corporation of New Jersey Filed Dec. 19, 1960, Ser. No. 76,546 13 Claims. (Cl. 230-143) This invention relates to fluid pumps, compressor, inotors and the like and more particularly to the type of such machines provided with a pair of interengaging rotors' corresponding bores of a casing which intermesh to form ian axially contracting or expanding chamber depending upon whether the machine is a pump or motor.

It has been customary in the past to synchronize the rotation of such rotors so that they will not contact, and furthermore to provide endthrust bearings which will avoid contact between the rotors or .any substantial pressure therebetween due to such contact. For the sake of eiciency the rotational speed of the rotors is high as compared with most rotary machines in which radial loads are comparable. This has led to diiiiculties in `that thrust bearings adapted to carry both radial and axial loads are not suitable ttor high speed operation when the radial load is substantial.

It is accordingly an object of this invention to provide a simple term of machine of the character described with an improved bearing and drive arrangement.

Other objects of the invention will be in part pointed out and in part obvious.

The drawing illustrates a preferred embodiment `of the invention as applied to an axial iiow compressor and includes FIGURE 1, -a horizontal longitudinal section through the compressor,

FIG. 2, :a vertical section taken longitudinally through the end portion of the female rotor yand the casing parts adjacent thereto, and

FIG. 3, a cross section taken along the line 3-3 of FIG. 1, looking inthe direction of the arrows.

Referring to the drawing the compressor comprises a casing within which fare airan ged two intersecting cylindrical bores 12 and 14 extending in the casing 10 lengthwise from the inlet head 16 to the head of the ydischarge end 18. Within casing 10 are mounted for rotation a male rotor 20 having lands 22 which cooperate with grooves 24 :of the female rotor 26. The lands 22 and the grooves 24 are helical 1and interengage in the manner well known in the art to form chambers which progress from the inlet end to the Adischarge end as rotors 2t) and 26 rotate. Such chambers displace fluid trapped between the rotors and force it out at the end of casing as discharge port 2S and thence to the disch-arge conduit 30 as indicated in FIG. 2.

Fluid is admitted in the box-like inlet head 16 and to the interior of the casing 10 at an inlet passage 32. Male rotor 20 is provided at its end adjacent inletpassage 32 with a shaft end 34 supported in head 16 and at the discharge end of the casing has another shaft end 36 of reduced diameter for support by head 18. Likewise female rotor 26 is provided .a shaft end 38 also mounted in head 16 and an additional shaft end 40 adjacent lthe discharge end of the casing and supported in head 18.

Also supported on head 16 is a bell end 42 supporting a drive shaft 44 having anti-friction bearings 46 supported by the bell end 42 and extending in this instance in line with rotor 26 into head 16 and journaled therein with antifriction bearings 4 mounted in head 16. Upon drive shaft 44 is mounted alielical gear Sti ladapted to drive a meshing pinion 52 on the end of shatt 34.

3,097,359 Patented `Iuly 9, 1963 ICC The helix :angle of pinion 52 is such that it tends to shove rotor 20 axially toward the discharge end of casing 10. The object of this is to counteract to some extent the thrust developed `as a result of the longitudinal pressure against lthe forward face of lands 22 as well as the reaction of female rotor 26 with which lands 22 engage.

In this construction no synchronizing gears between rotors 20 and 26 are provided. The sole driving force for rotating female rotor 26 is produced by interengagement of lands 22 with grooves 24. For lubrication, oil may be introduced with the air being pumped by suitable apparatus (not shown). Such oil will also tend to cool fluid being compressed and partly assist in producing a seal at the sealing edges.

As has been before stated one object ot the construe tion is to eliminate as far as possible thrust bearings and to use, instead, those )adapted for radial loads. To this end, both ends of the rotors `are supported by straight radial load bearings. Accordingly `shaft 34 is mounted in straight roller bearings 54 as is also shaft 38 in roller bearing 56. Bearing 54 is mounted in the inlet head 16 Aand maintained in position by a keeper ring 5S. The inner race of bearing S4 acts las an abutment for pinion 52 which is held on the end of shaft 34 by :a bolted plate 60. Likewise bearing 56 is held in place in head 16 by a keeper ring 62 and on the yend of shaft 38 by a retainer ring 64. At the discharge end of rotor 20, shaft 36 is provided with a straight roller bearing of the radial load type 66 supported in head 1S fand lshaft 4t) is likewise provided with a similar straight roller bearing 68 -supported in head 18.

Depending upon the pressures existing within casing 10 there is apt to be end thrust in the direction of inlet head 16 and this is adapted to be received by a combination end thrust and radial load bearing of the ball type 69 on the end of shaft 36. Likewise such thrust is taken on the female rotor 26 by a lball type combination axial thrust and radial load ball bearing 70.

Bearings 66 and 69 abut each other and `are held in place on shaft `36 by a bolted cap 72 on the end of shaft 36 which engages the inner races to abut a spacer collar or sleeve '74 encircling shaft 36 and bearing against the main centr-al body of rotor 20. `Likewise a bolted cap 76, bearing against the inner race of bearing 710 hol-ds bearings 68 and 76 rigidly in place against a spacer sleeve 78 abutting the central main body ott rotor 26. With respect to head 18, bearings 66 rand 69 Iare held in place by a suitable cap bearing against the outer race of hearing 69, and an additional cap 82 bears against the outer race of bearing 70 to hold itis place in head 18.

In the operation of this machine end thrust is mainly in the direction of the inlet end of casing 10. However on coming up to speed there maybe thrust in the opposite direction. To receive this thrust the invention provides a thrust plate 84 having an inner bearing face 86 which may be `lined with a suitable `bearing metal or the plate itself may be yconstructed of aluminum. This bearing face is adapted to contact the end faces of the main body of rotors `2t? `and 26 indicated at 88 `and 90, respectively, of the rotors 20 and 26. These faces should be smooth tinished and they serve as sealing surfaces to prevent leakage at the ends of the rotors as Awell `as bearing surfaces. Slight `clearance lshould be provided and this is aiforded by forming sleeves `74 `and '73 with a slightly greater length than the thickness of bearing plate 84. Ordinarily a very few thousandths of an inch will sutice for this purpose. Bearing plate 84 is held in place in Ia -bore 92 in the attaching flange of head 18 the lateral dimensions of plate 84 'being slightly in excess of the limits of bores 12 and 14. Suitable bolts 94 cl-amp plate 84 against the end of casing 10. Leakage is prevented by a sealing ring 96 at the joint with casing 10.

The operation o-f this type of machine has been indicated hereinbefore. It is usual for such a machine to have more grooves in the female rotor than lands -i-n the male rotor which permits a stronger construction of rotor. This has been -indicated in FIG. 3 in which as shown there are six grooves las against four lobes. The difference in axial pressures resulting is off-set by the slower speed of the female rotor.

As may be inferred from the `bell housing 42 this compressor may be mounted as part -of a combustion engine or electric engine driven unit (not shown), the bell housing 4Z being adapted to house the drive coupling (not shown). The outer end of the casing is provided with suitable `lugs 100 for bolting to feet as indicated at lill for support. With engine drive operating `speeds are apt to be variable and end thrusts lare correspondingly variable. The construction above described lends itself to this application very well since reversals of end thrusts are apt to occur, though mainly the thrust is in one direction when of any substantial value.

Thus, -by the above yconstruction are accomplished, among others, the objects hereinbefore referred to.

We claim:

1. An elastic iuid compressor of the screw rotor type, comprising a casing having parallel intersectin-g bores with inlet and discharge passages at opposite ends thereof, interengaging male and female rotors in said bores and providing a direct drive therebetween, a drive shaft rotatably mounted at the inlet end of the casing, a helical drive gear fixed to said drive shaft and rotated thereby, each of said rotors having a shaft extending axially at each rotor end, a helical driven rgear on the male rotor shaft at the inlet end of the casing and in mesh with said drive gear wherein the helix angle of the gear teeth acts to produce axial thrust toward the discharge end, straight radial load bearings on said shaft at both the inlet and discharge ends of the casing, .and an additional bearing on a shaft of each rotor to counteract thrust in the direction of the casing inlet end.

2. An elastic fluid compressor of the screw rotor type, comprising a casing having parallel intersecting bores with inlet and discharge passages at opposite ends thereof, interengaging male and female rotors in said bores and providing a direct drive therebetween, a drive shaft rotatably mounted at the inlet end of the casing, a helical `drive gear fixed to said drive shaft and rotated thereby, each of said rotors having a shaft extending axially at each rotor end, a helical driven gear on the male rotor shaft at the inlet end of the casing and in mesh with said drive gear wherein the helix angle of the gear teeth acts to produce axial thrust toward the discharge end, straight radial load bearings on said shaft at both the inlet and discharge ends of the casing, and an additional bearing on a sha-ft of each rotor adjacent the casing discharge end to counteract thrust in the direction of the casing inlet end.

3. An elastic fluid compressor o-f the screw rotor type, comprising a casing having parallel intersecting bores with inlet and discharge passages at opposite ends thereof, interengaging male and female rotors in said bores and providing a direct drive therebetween, a drive shaft rotatably mounted at the inlet end of the casing, a helical drive gear fixed to said drive shaft and rotated thereby, each of said rotors having a shaft extending axially at each rotor end, a helical driven gear on the male rotor sha-ft at the inlet end lof the casing and in mesh with said drive -gear wherein the helix angle of the gear teeth acts to produce axial 'thrust toward the discharge end, straight radial load roller bearings on said shaft at both the inlet and discharge ends of the casing, and an additional bearing on the shaft of each rotor adjacent the casing discharge end to counteract thrust in the direction of the casing inlet end.

4. An elastic fluid compressor of the screw rotor type, comprising `a. `casing having parallel intersecting bores with inlet and discharge passages at opposite ends thereof, interengaging male and female rotors in said bores and prod viding a direct drive therebetween, a drive shaft rotatably mounted at the inlet end of the casing, a helical drive gear fixed to said drive shaft and rotated thereby, each of said rotors having a `shaft extending axially at each rotor end, a helical driven gear on the male rotor shaft at the inlet end of the `casing and in mesh with said drive gear wherein the helix angle of the gear teeth acts to produce axial thrust toward the discharge end, straight radial load roller bearings on said shaft at both the inlet and discharge ends of the casing, and an additional bearing of the ball type on a shaft of each rotor adjacent the casin-g discharge end to counteract thrust in the direction of the casing inlet end.

5. An elastic fluid compressor of the screw rotor type, comprising a casing having parallel intersecting bores with inlet and discharge passages at opposite ends thereof, interengaging male and female rotors in said bores, such intere-ngagement providing the sole driving force for said female rotor, each of said rotors having a shaft of reduced diameter extending axially at each rotor end, a helical gear drive on the ina-le rotor shaft at the inlet end of the casing wherein the helix angle of the gear teeth acts to produce axial thrust toward the discharge end, straight radial load bearings on each shaft at both the inlet and discharge ends of the casing, and an addition-al bearing on a sha-ft of each rotor adjacent the casing discharge end to counteract thrust in the direction of the easing inlet end.

6. An elastic fluid compressor of the `screw rotor type, comprising a casing having parallel intersecting bores with inlet and discharge passages at opposite ends thereof, interengaging -male yand female rotors in said bores, Isuch interengagernent providing the `sole `driving force for said female rotor, each of said rotors having a shaft of reduced diameter extending laxially at each rotor end, a helical gear drive on the lmale rotor shaft 4at the inlet end of the casing wherein the helix angle of the :gear teeth acts to produce axial thrust toward the discharge end, straight radial load bearings on each said shaft at both the inlet and discharge ends of the casing, and an additional bearing on a shaft of each rotor to counteract thrust in the direction of the casing inlet end.

7. An elastic fluid compressor of the screw rotor type, comprising a casing having parallel intersecting bores with inlet and discharge passages at opposite ends thereof, interengaging male .and female rotors in said bores, such interengagement providing the sole driving lforce for said lfemale rotor, each of said rot-ors having a shaft of reduced diameter extending axially at each rotor end, a helical gear `drive on the male rotor shaft at the inlet end of the casing wherein the helix angle of the gear teeth acts to produce axial thrust toward the discharge end, straight radial load roller bearings on each said shaft at lboth the inlet and discharge ends of the casing, and an additional bearing on a shaft of each rotor adjacent the casing discharge end to counteract thrust in the direction of the casing inlet end.

8. An elastic iluid compressor of the screw rotor type, comprising a casing having parallel intersecting bores with inlet and discharge passages at opposite ends thereof, interengaging male and female rotors in said bores, such interengagement providing the sole driving force for said female rotor, each of said rotors having a shaft of reduced dia-meter 'extending axially at the rotor end, a helical gear drive on the male rotor shaft at the inlet end of the casing wherein the helix angle of the gear teeth acts to produce axial thrust toward the discharge end, straight radial load roller bearings on each said shaft at both the inlet and discharge ends of the casing, and an additional bearing of the ball type on a shaft of each rotor to counteract thrust in the direction of the casing inlet end.

9. An elastic `iluid compressor of the screw rotor type, comprising a casing having parallel intersecting hores with inlet and -discharge passages at opposite ends thereof, interengaging male and female rotors in said bores, such interengagernent providing the sole driving force 4for said female rotor, each of said rotors having a shaft of reduced diameter extending axially at each rotor end, a helical gear drive on the male rotor shaft at the inlet end of the casing wherein the helix angle iof the gear teeth acts to produce axial thrust toward the discharge end, straight radial load bearings on each said shaft at both the inlet and discharge ends of the casing, an `additional hearing on a shaft of each rotor to counteract thrust in the direction of the casing inlet end, and an axial thrust receiving plate having an anti-friction face abutting the rotor ends and interposed between said bearings and the central portions of said rotors at the discharge end of the casing.

10. An elastic fluid compressor `of the screw rotor type, comprising a casing having parallel intersecting bores with inlet and discharge passages at opposite ends thereof, interengaging male and female rotors in said hores, such interengagement providing the sole driving force for said female rotor, each of said rotors having a shaft of reduced diameter extending axially `at each rotor end, a helical gear drive on the male rotor shaft at the inlet end of the casing wherein the helix angle of 4the gear teeth acts to produce axial .thrust toward the discharge end, straight radial load bearings on each said shaft at .hoth the inlet and discharge ends of the casing, an additional bearing on a shaft of each rotor to counteract thrust in the direction of the casing inlet end, an axial thrust receiving plate having an antifriction face for abutting the rotor ends and interposed between said `bearings and the central portions of said rotors at the discharge end of the casing, and means to provide an axial clearance between said rotors and said plate.

11. An elastic fluid compressor of the -screw rotor type, comprising a casin-g having parallel intersecting 'hores with inlet and discharge passages at opposite ends thereof, interengaging male and female rotors 4in said bores, such interengagement providing the sole driving force for said female rotor, each of said rotors having a shaft of reduced diameter extending axially at each rotor end, a helical gear drive on the male rotor shaft at the inlet rend of the casing wherein the helix angle of the gear teeth acts to produce axial thrust toward the discharge end', straight radial load bearings on each said shaft at hoth the inlet `and dis charge ends of the casing, an additional bearing on a shaft of each roto-r to counteract thrust in the direction of the casing inlet end, an axial thrust receiving plate having an antifriction face `for abutting the rotor ends and interposed between said bearings and the central portions of said rotors at the discharge end of the casing, and means to provide an axial clearance between said rotors and said plate including a spacer sleeve on such shaft extending through said plate.

l2. An elastic fluid compressor of the screw rotor type, comprising a casing having parallel intersecting bores with inlet and discharge passages at opposite ends thereof, interengaging male and female rotors in said bores, such interengagement providing the sole driving force for said female rotor, each of said rotors having Ia shaft of reduced diameter extending laxially at each rot-or end, a helical gear drive on the male rotor shaft at the inlet 'end of the casing wherein the helix angle of the `gear teeth acts to produce axial thrust toward the discharge end, straight radial load bearings on each said shaft at both the inlet and discharge ends of the casing, an additional hearing on a shaft of each rotor to counteract thrust in the direction of the casing inlet end, an axial thrust receiving plate having an `antifriction face for abutting the rotor ends and interposed lbetween said bearings and the central portions of said rotors at the discharge end of the casing, and means to provide an axial clearance between said rotors and said plate including ra 4spacer sleeve on such shaft extending through said plate and having an axial length slightly `greater than the thickness of said plate.

13. An elastic fluid compressor of the screw rotor type, comprising a casing having parallel intersecting hores with inlet and discharge passages iat opposite ends thereof, interengaging male and female rotors in said bores, such interengagement providing the sole driving 'force for said female rotor, each of said rotors having a shaft of reduced diameter extending axially at each `rotor end, a helical gear drive on the male rotor shaft at the inlet end of the casing wherein the Ahelix angle of the gear teeth acts to produce axial thrust toward the discharge end, straight radial load bearings on each said shaft `at both the inlet and discharge ends of the casing, an additional bearing on `a shaft of each rotor to counteract thrust in the direction of the casing inlet end, an axial thrust receiving plate having an antifriction face for abutting the rotor ends and interposed between said ibearings `and the central portions of said rotors at the discharge end of the casing, land means to provide an axial clearance Ibetween said rotors and said plate including a spacer sleeve on such shaft extending through said plate and having an `axial length slightly greater than the thickness lof said plate, said plate forming ian abutment for said thrust bearings.

References Cited in the le of this patent UNITED STATES PATENTS 2,014,932 Hallett Sept. 17, 1935 2,243,874 Lysholm June 3, 1941 2,287,716 Whiteld June 23, 1942 2,410,341 Delamere Oct. 29, 1946 2,477,004 Paget July 26, 1949 2,578,196 Montelius Dec. ll, 1951 2,868,442 Nilsson Jan. 13, 1959 2,935,247 Trulsson May 3, 1960 FOREIGN PATENTS 648,055 Great Britain Dec. 28, 1950 

1. AN ELASTIC FLUID COMPRESSOR OF THE SCREW ROTOR TYPE, COMPRISING A CASING HAVING PARALLEL INTERSECTING BORES WITH INLET AND DISCHARGE PASSAGES AT OPPOSITE ENDS THEREOF, INTERENGAGING MALE AND FEMALE ROTORS IN SAID BORES AND PROVIDING A DIRECT DRIVE THEREBETWEEN, A DRIVE SHAFT ROTATABLY MOUNTED AT THE INLET END OF THE CASING, A HELICAL DRIVE GEAR FIXED TO SAID DRIVE SHAFT AND ROTATED THEREBY, EACH OF SAID ROTORS HAVING A SHAFT EXTENDING AT EACH ROTOR END, A HELICAL DRIVEN GEAR ON THE MALE ROTOR SHAFT AT THE INLET END OF THE CASING AND IN MESH WITH SAID DRIVE GEAR WHEREIN THE HELIX ANGLE OF THE GEAR TEETH ACTS TO PRODUCE AXIAL THRUST TOWARD THE DISCHARGE END, STRAIGHT RADIAL LOAD BEARINGS ON SAID SHAFT AT BOTH THE INLET AND DISCHARGE ENDS OF THE CASING, AND AN ADDITIONAL BEARING ON A SHAFT OF EACH ROTOR TO COUNTERACT THRUST IN THE DIRECTION OF THE CASING INLET END. 